I have not seen this behavior on any of my Macs, and what you're describing is not normal.
I'm not saying that you're necessarily wrong, but there are many different things that could also cause this. Some investigation would be in order before making that claim. (Spotlight indexing via mdworker is the usual first culprit for this kind of behavior, in my experience.)
You should be able to see what's causing the extra load by keeping an eye on Activity Monitor.
Last couple times I got tons of beachballs system-wide for no clear reason, it was because I was doing Android dev and had the emulator running, or, earlier, because I hadn't yet switched to Safari. Both FF and Chrome did that to me, though Chrome was slightly better about it.
I'm not saying that you're necessarily wrong, but there are many different things that could also cause this. Some investigation would be in order before making that claim. (Spotlight indexing via mdworker is the usual first culprit for this kind of behavior, in my experience.)
You should be able to see what's causing the extra load by keeping an eye on Activity Monitor.